The reason why you can’t bring metal objects to the MRI is because carrying metal can affect the test results, injure the patient or damage the instrument. 1. Affecting the examination results: MRI technology can be used for the examination of tumors, musculoskeletal system diseases and cerebrovascular diseases. Usually, before the examination, you need to remove metal items such as watches, necklaces, dentures, etc. The main reason is that metal will interfere with the magnetic field, which will not clearly show the signals of normal tissues as well as abnormal tissues, thus affecting the examination results. 2. Damage to the patient’s body or instrumentation: MRI mainly scans the body through a powerful magnetic field, which has a relatively large adsorption force on metal. If you wear a metal object in the process of examination, the magnetic field will adsorb the metal object, which is easy to injure the patient. When the metal adsorption speed is large, directly hit the equipment, can also lead to damage to the equipment. Patients with metallic substances implanted in the body such as pacemakers, metal stents, screws, steel plates, etc. are prohibited from undergoing an MRI examination. It is recommended that patients carefully understand the precautions to be taken before undergoing an MRI examination and that they do so under the supervision of their doctor.